1. Field of the Invention
The present invention relates to a trim and tilt system for use with an outboard motor mounted on a marine craft.
2. Description of Related Art
Conventional trim and tilt systems include a unitary trim and tilt cylinder apparatus, as disclosed in U.S. Pat. No. 5,032,094, issued Jul. 1, 1991 to Sadaji Katogi, hereinafter Katogi. Katogi discloses a trim and tilt system for trimming and tilting an outboard propulsion unit on a boat. The trim and tilt system disclosed by Katogi includes a unitary trim and tilt cylinder apparatus having a tilt cylinder unit and a trim cylinder unit, a stem bracket adapted to be mounted on the transom of the boat, a swivel bracket for supporting the outboard propulsion unit, the swivel bracket being pivotally supported on an upper end of the stem bracket, and a hydraulic pressure circuit for actuating the tilt cylinder unit and the trim cylinder unit. The trim and tilt cylinder apparatus has an upper end pivotally supported on the stern bracket and a lower end pivotally supported on the swivel bracket.
The trim and tilt system disclosed by Katogi has the disadvantage of undue stress being applied to the trim cylinder units at a point of contact of a trim rod of each of the trim cylinder units with the swivel bracket. This excessive stress is in part due to the unitary construction of the trim and tilt cylinder apparatus. As the outboard propulsion unit pivots during the trimming and tilting procedure, the angle of the trim rods of each of the trim cylinder units changes with respect to the swivel bracket. The weight of the propulsion unit is therefore applied to the trim rod through the swivel bracket at various angles throughout the trimming procedure. This leads to a considerable amount of transverse stress being applied between the trim rods and their respective trim cylinders, leading to undue wear and fatigue.
There is therefore a need for a new and improved trim and tilt system that reduces the stress experienced by trim cylinder units during the trimming of a marine propulsion unit.